1. Field of the Invention
The present invention relates to a washing machine, and more particularly, to a drum type washing machine having a water turbine at a front of a rotary tub, so as to raise wash water with detergent and spray the mixture on laundry in a washing operation.
2. Description of the Related Art
Generally, washing machines are used to wash laundry by rotating a cylindrical rotary tub containing the laundry and wash water therein. Such washing machines have been typically classified into drum type washing machines and vertical shaft type washing machines. The drum type washing machines are designed such that a rotary tub is horizontally set in a cabinet and is rotated around a horizontal axis of the cabinet in opposite directions to repeatedly move the laundry seated on an internal surface of the rotary tub upward and allow the laundry to be dropped from the top to the bottom inside of the rotary tub to wash the laundry. In the vertical shaft type washing machines, a rotary tub with a pulsator is vertically set in a cabinet and is rotated around a vertical axis of the cabinet in opposite directions. In vertical shaft type washing machines, laundry inside the rotary tub are washed by forced water currents generated by the pulsator.
FIG. 1 shows the internal structure of a conventional drum type washing machine (“washing machine”). The washing machine includes a cabinet 1 which defines an outer appearance of the washing machine. A cylindrical water tub 2 is horizontally set in the cabinet 1, and receives wash water therein. A rotary tub 3 having a cylinder shape drum is rotatably set in the cylindrical water tub 2, and is perforated on its sidewall to have spin-drying perforations 3a. The drum type washing machine also has a drive motor 4 which rotates the rotary tub 3.
The cabinet 1 has an opening to allow a user to place the laundry in the rotary tub 3 or remove the laundry from the rotary tub 3. A front door 5 is hinged to the opening of the cabinet 1 to selectively close the rotary tub 3. Lifters 6 are positioned on an internal surface of the rotary tub 3 at regular intervals. In response to rotating of the rotary tub 3, the lifters 6 repeatedly move the laundry seated on the internal surface of the rotary tub 3 upward and drop the laundry from the top to the bottom inside of the rotary tub 3 to wash the laundry.
The cabinet 1 is provided at its upper portion with a water supply hose 7 and a detergent container 8. A circulation pump 9 and a drain pump 10 are provided at a bottom of the cabinet 1.
Unlike the vertical shaft type washing machines with a rotary tub vertically set in a cabinet, which wash laundry inside the rotary tub with forced water currents generated by a pulsator, the drum type washing machines consume a small quantity of water. However, the drum type washing machines take a longer time to wash the laundry due to a washing method used, that is, lifting and dropping of the laundry. In the drum type washing machines, detergent is also not rapidly dissolved in wash water and undesirably lays thick on a bottom of a water tub.
To solve the above problem, the circulation pump 9 is installed in the drum type washing machine shown in FIG. 1. In other words, the circulation pump 9 is used to move the detergent accumulated on the bottom of the cylindrical water tub 2 upward, which is not dissolved in the wash water, together with the wash water to rapidly dissolve the detergent in the wash water and wet the laundry.
A wash operation of the conventional drum type washing machine described above is as follows. First, wash water with detergent is fed to the cylindrical water tub 2 through the water supply hose 7 and the detergent container 8. At this time, the wash water having the detergent is supplied into the rotary tub 3, which contains the laundry therein, through the perforations 3a formed on the sidewall of the rotary tub 3 until a predetermined wash water height is achieved. Next, the rotary tub 3 is repeatedly rotated in alternating directions at regular intervals by the drive motor 4. When the rotary tub 3 is rotated, the lifters 6 provided on the internal surface of the rotary tub 3 move the laundry upward and allow the laundry to be dropped from a height inside the tub 3 to wash the laundry. At the same time, the circulation pump 9 is actuated to raise the wash water with the detergent from the bottom to the top of the cylindrical water tub 2 through a circulation hose 11 connected to an inlet and outlet of the circulation pump 9 and upper and lower ends of the cylindrical water tub 2, and discharge the wash water from the top of the cylindrical water tub 2 to wet the laundry.
After a washing operation is completed in a set period of time, the drain pump 10 is actuated to discharge the wash water to the outside through a drain hose 12. Thereafter, the washing machine performs a rinsing operation to remove the detergent from the laundry. Finally, the drive motor 4 rotates the rotary tub 3 at a high speed while actuating the drain pump 10 to spin-dry the laundry, thus completing the wash operation.
However, in the conventional drum type washing machine, only a small portion of the wash water with detergent is raised from the bottom to the top inside of the cylindrical water tub 2 and discharged to the rotary tub 3 by the circulation pump 9 and the circulation hose 11 during the washing operation. That is, only a part of the wash water flows into the rotary tub 3 through the perforations 3a during the rotation of the rotary tub 3, and the remaining wash water flows down to the bottom of the cylindrical water tub 2 along the external surface of the rotary tub 3. Accordingly, the conventional drum type washing machine is incapable of sufficiently wetting the laundry. Therefore, additional time is required to properly wet the laundry, further extending the time required to wash the laundry.
Furthermore, with use of the circulation pump 9 and the circulation hose 11 to wet the laundry, manufacturing cost is increased. Also, operational noise as well as vibration are increased by the operation of the circulation pump 9. Such noise and vibration give negative impressions to consumers as to the quality of the washing machine, and lower durability of components in the washing machine.